The present invention relates generally to the testing of integrated circuit devices and, more specifically, to the testing of integrated circuit devices which require optical access to the active surfaces thereof in order to perform proper testing.
The manufacture of integrated circuits typically begins with a process in which multiple layers of the integrated circuit are formed via a photolithographic process. Typically, during the photolithographic process, several integrated circuits are manufactured on a single silicon substrate which is commonly referred to in the industry as a xe2x80x9cwaferxe2x80x9d.
A completed integrated circuit includes a number of circuit layers and a plurality of electrical connection sites to facilitate electrical interface between the integrated circuit and the electronic device in which the integrated circuit is eventually installed. When the manufacture of the integrated circuits on a wafer is completed, the wafer is broken apart such that the integrated circuits contained thereon are separated into individual units.
Integrated circuits still located on a wafer, i.e., before the wafer is broken apart as described above, may be referred to herein as xe2x80x9cwafer integrated circuitsxe2x80x9d.
After separation, each integrated circuit is typically mounted into an integrated circuit xe2x80x9cpackagexe2x80x9d. A package is a housing which generally includes a plurality of electrical connectors, e.g., pins, around its periphery. The housing also includes electrical connections between the integrated circuit electrical connection sites and the package pins. In this manner, the package provides an interface between the integrated circuit and the electronic device in which the package is eventually to be installed.
Two types of integrated circuit devices have become increasingly common. An image capture chip is an integrated circuit device which is capable of capturing a two dimensional image, e.g., a page of printed text. Image capture chips generally consist of a one or two-dimensional photosensor array, which may, for example, be an array of photodetectors. Image capture chips are typically used in devices such as camcorders and digital cameras. One example of a commercially available image capture chip is a Model No. VV6850 currently offered for sale by Vision Company at 571 West Lake Avenue, Suite 12, Bay Head, N.J., 08742.
A display chip is an integrated circuit device which includes an array of display pixels which can each be selectively energized to assume various visual conditions, e.g., reflective vs. non-reflective or light emitting vs. non-light emitting. Display chips are typically used in devices such as displays for digital cameras or for cellular telephones. One example of a commercially available display chip is a Model 320C Color xe2x80x9cCyberDisplayxe2x80x9d currently offered for sale by Kopin Corporation, 695 Myles Standish Blvd., Taunton, Mass. 02780.
It is desirable to test integrated circuit devices at various stages in the development of the devices. It is common, for example, to inspect integrated circuits while the integrated circuits are still part of a wafer (i.e., wafer integrated circuits), as described above. It is also common to test integrated circuit packages after the integrated circuits have been installed into packages. This common procedure of testing at various stages of development allows defective integrated circuit products to be detected early in the manufacturing process.
Testing of integrated circuit devices is commonly accomplished through the use of automated test equipment. In the testing of wafer integrated circuits, as described above, it is common to mount a wafer to be tested within an automated robotic handling device. A test head is then moved into proximity with the handling device. The test head contains a plurality of electrical contact probes which are adapted to make electrical contact with the electrical connection sites of a wafer integrated circuit. The handling device moves the wafer toward the test head until the electrical connection sites of a first integrated circuit come into contact with the contact probes of the test head. In this manner, the test head is able to conduct electrical signals between the integrated circuit electrical connection sites and the appropriate testing equipment in order to accomplish testing of the integrated circuit device in a conventional manner.
After the first wafer integrated circuit has been tested, as described above, the handling device moves the wafer away from the test head, such that the integrated circuit connection sites are no longer in contact with the test head contact probes. The handling device then indexes the wafer so that a second integrated circuit on the wafer is aligned with the test head probes. The process described above is then repeated for the second and for subsequent wafer integrated circuits until all of the integrated circuits on the wafer have been tested.
When testing integrated circuit packages, a package to be tested is typically held within an automated robotic handling device. A test head is fixed in proximity with the handling device. The test head contains a plurality of pin receptors, e.g., socket receptacles, which are adapted to make electrical contact with each of the pins of the package. A plunger in the handling device then urges the integrated circuit package toward the test head until the package pins engage with the test head pin receptors. In this manner, the test head is able to conduct electrical signals between the pins of the integrated circuit package and the appropriate testing equipment in order to accomplish testing of the integrated circuit package in a conventional manner.
After an integrated circuit package has been tested, the handling device then causes another integrated circuit package to move into proximity with the test head. The second integrated circuit package is then tested in a manner as described above. The process is then repeated until the desired number of integrated circuit packages have been tested.
As described above, most integrated circuits and integrated circuit packages can be effectively tested merely by providing electrical interface between the circuit or package and a testing machine. In the case of an image capture chip, however, it is also necessary to provide a light source in order to test the chip. The light source may take the form of a simple light generation device. Alternatively, the light source may include both a simple light generation device and a filter designed to impinge a specific pattern of light onto the active surface of the chip. To test an image capture chip, the light source may be selectively activated while electrical output from the image capture chip is monitored to verify that the image capture chip is generating the proper signals in response to the supplied light and, thus, operating properly.
In order to effectively test a display chip, visual monitoring, e.g., via a camera, of the display chip is required in order to verify that the display chip is generating the proper display dictated by the electrical signals supplied to the display chip. It is desirable for proper testing, for example, that the operation of each display pixel on the display chip be visually verified in order to assure that all of the pixels are operating properly. To facilitate this visual monitoring, a light source may also be required. Some display chips, however, generate light and, thus, may not require a light source.
Current commercially available automatic testing equipment, as generally described above, lacks the provision of either a light source or of a visual inspection system. Accordingly, current automatic testing equipment is incapable of appropriately testing image capture chips and display chips.
Accordingly, it would be desirable to provide an automatic testing system which overcomes the problems described above and which is capable of effectively inspecting image capture and display chip integrated circuit devices.
The present invention is directed to a method and apparatus for testing integrated circuit package devices using automatic testing equipment. Specifically, the automatic testing equipment may be provided with a light source to enable the testing of image capture type integrated circuit devices. Alternatively, the automatic testing equipment may be provided with an imaging device, e.g., an electronic camera, or both a light source and an imaging device to additionally enable the testing of display type integrated circuit devices.
Integrated circuit packages may be tested using a conventional test head in combination with a modified handling device. The modified handling device may include a plunger to apply pressure to the integrated circuit package being tested in a conventional manner. The plunger, however, may be modified by the addition of a mirror block which allows optical access to the active surface of the integrated circuit package even while pressure is being applied by the plunger. In this manner, a light source and/or an imaging device located within the modified handling device is afforded optical access to the active surface of the integrated circuit package while testing is being accomplished.
Wafer integrated circuits may be tested using a conventional handling device in combination with a modified test head. The modified test head may include a mirror block which allows optical access to the active surface of the wafer integrated circuit while testing is being carried out. In this manner, a light source and/or an imaging device located within the modified test head is afforded optical access to the active surface of the wafer integrated circuit while testing is being accomplished.